1.1. Which of the following statements is/are true?

1. A nerve impulse is carried across a synapse by an electrical signal.

2. Motor neurones carry chemical signals from the CNS to effectors.

3. Reflexes involve the conscious part of the brain.

1.2. Figure 3 shows part of the nervous system involved in a reflex action when a person steps on a sharp pin.

Figure 3

Name part X.

1.3. Reflexes in the eyes cause a blink if something quickly comes towards them.

Explain why such reflexes are important.

1.4. The average speed of a nerve impulse in the human body is 100 metres per second.

A man, who is 2 metres tall, accidentally stubs his toe in the dark.

Calculate the time it takes the nerve impulse to travel to his brain.

Give your answer in milliseconds; 1 000 milliseconds = 1 second.

Use the equation:

$Time=\frac{Distance}{Speed}$